POTS: A Pediatric Focus

(From the November 2013 Issue of PediatricsOnline)

By the time the 16-year-old patient found her way to the office of pediatric neurologist Geoffrey L. Heyer, MD, at Nationwide Children’s Hospital, she had seen a handful of other physicians for her chronic headaches and frequent bouts of dizziness. Unable to diagnose her problem, at least one doctor mentioned malingering as a possible cause and recommended she see a psychiatrist.

After an examination and a tilt-table test, the girl and her parents finally had a diagnosis: postural orthostatic tachycardia syndrome (POTS), an autonomic nervous system disorder that can cause a variety of symptoms related to positional changes, including a racing heart, headaches, dizziness, fainting, nausea, excessive sweating, mood changes and a host of other symptoms. The condition is largely misunderstood and often misdiagnosed, according to Dr. Heyer, medical director of the POTS Clinic at Nationwide Children’s.

“When they get to me, many of my patients have been referred to several specialists for their many different symptoms,” Dr. Heyer says. “Knowing that all complaints can be explained by a single diagnosis often offers some relief.”

Nationwide Children’s created the POTS clinic in November 2011 to facilitate diagnosis and treatment and advance research into a condition that affects mostly girls and women age 12 to 50. For reasons that aren’t well understood, when a person with POTS stands up, blood pools in the lower extremities. To compensate, the heart rate jumps dramatically, increasing by more than 30 beats a minute, a condition known as tachycardia. Meanwhile, the drop in blood supply to the brain causes dizziness and sometimes fainting. Although POTS hasn’t been shown to damage the heart or brain, the disorder can be disruptive, leading to missed school and work and, sometimes, depression.

“We don’t know what causes POTS, but we do know that it is related to blood circulation and pooling of blood in the legs, pelvis and abdomen,” Dr. Heyer says. “When we stand up, several things must happen to push blood up to the heart and to help the heart pump blood effectively against gravity. POTS patients have one or more problems that cause excessive blood pooling or inadequate blood return to the heart when they sit or stand up."

More than 100 patients have been diagnosed with POTS since the clinic opened, many referred to Dr. Heyer’s team for headaches and dizziness. The prevalence of POTS in the U.S. is unknown, but better recognition of the disorder has led to increasing numbers of patients diagnosed, Dr. Heyer says.

“We don’t know the true frequency of POTS in children, but there’s reason to believe that it is not a rare disorder,” he says, adding that one of the problems is a lack of consensus over diagnostic criteria for younger children and adolescents.

At Nationwide Children’s, POTS is diagnosed using a tilt-table test. After other conditions have been ruled out, suspected POTS patients are placed on a tilt table after fasting for three hours. They lie on the table for 30 minutes. While wearing heart-rate and blood pressure monitors, the table is tilted to a 70-degree angle with the patient’s head upright. If a patient has symptoms during the test (lightheadedness, headaches, nausea, etc.) that correspond with an increase in heart rate of at least 30 beats per minute, and no substantial drop in blood pressure, the patient has POTS.

In a study published earlier this year in the journal Headache, Dr. Heyer and his colleagues identified a number of symptoms that were predictive of POTS. Researchers studied 70 adolescent patients referred to the POTS clinic for evaluation. They found that patients who experienced a headache upon standing, had lightheadedness that preceded or triggered headaches, or had a new onset or worsening of motion sickness were more likely to test positive for POTS.

These findings help address a lack of research on POTS in pediatric patients. The frequency of POTS episodes in menstruating teenage girls points to a possible hormone link. Studies show that in some cases, levels of norepinephrine are elevated, which could explain the sometimes drastic mood changes and profuse sweating that POTS patients often report. Another possibility is a problem in the pathways that carry messages from the brain to the heart. Adults with the disorder often develop POTS symptoms following a viral illness, surgery or prolonged bed rest. However, these triggers are rarely present in children, Dr. Heyer says.

The first line of therapy is usually designed to address the availability of sodium in the bloodstream. Patients often increase their salt intake, drink more fluids and in some cases, take a medication that increases the amount of sodium absorbed by the body. When these treatments fail, physicians might prescribe a type of anti-depressant or a drug that decreases norepinephrine release. Some studies suggest that wearing a compression device could improve blood flow and reduce the symptoms of POTS. Dr. Heyer plans to study that further in a clinical trial this year.

“As we see more patients, we learn more about this disorder,” Dr. Heyer says. “And the more we learn, the more help we can offer our patients.”